Module 10 Flashcards

1
Q

Epidemiology

A

The investigation of how health events in a population are patterned or distributed

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2
Q

Purpose of Epidemiology

A

Purpose is to provide a basis for developing:

  1. prevention strategies for groups at risk
  2. disease control measures for affected groups
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3
Q

Descriptive Epidemiology

A

concerned with WHAT WHO WHERE and WHEN

Focuses on the frequency and distribution of states of health within a population

*focus of this class

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4
Q

Analytic Epidemiology

A

concerned with HOW and WHY

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5
Q

Examples of What in Descriptive Epidemiology

A

What is the health event

what is the disease

what is the outcome

how severe is it

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6
Q

Examples of Who in Descriptive Epidemiology

A

Who are at risk

who is ill

(person)

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7
Q

Examples of Where in Descriptive Epidemiology

A

Where did the health event occur

How widespread is the illness

(place)

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8
Q

Examples of When in Descriptive Epidemiology

A

When did the health event happen

how long did the illness last

(time)

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9
Q

Characteristics included in the WHO/person of descriptive epidemiology

A

Age, gender, ethnicity

genetic predisposition

concurrent disease

diet and exercise

risk taking behaviors such as smoking

socio economic status

marital status

education and occupation

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10
Q

Characteristics included in the WHERE/place of descriptive epidemiology

A

Presence of agents or vectors

climate and geography

population density

economic development

customs and practices of the area

medical care and access

regional crime and unemployment rates

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11
Q

Characteristics of the WHEN/time of descriptive epidemiology

A

Calendar time

time since an event

physiologic cycles

age (time since birth)

seasonality

temporal trends

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12
Q

Basic Measures of Descriptive Epidemiology

A

Counts

Ratio

Proportion

Attack Rate

Prevalence

Prevalence Rate

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13
Q

Counts

A

simplest measure to describe how many cases

ex: 20 colds occurred

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14
Q

Ratio

A

relationship between two counts, numerator is not included in the denominator

(# those that are ill, divided by [compared to] # those that are not)

ex: 1:3 ratio of sick to healthy

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15
Q

Proportion

A

relationship between two counts

numerator is included in the denominator, part of a whole

(# of those that are ill divided by everyone)

ex: 20/100

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16
Q

Attack Rate

A

Number of persons that develop a disease divided by the number of persons exposed to the causative agent (used commonly in food Bourne illness investigations or flu outbreaks)

ex: Developed/Exposed = 5 w food poisoning / 20 total exposed

*exposed includes those who developed disease

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17
Q

Prevalence

A

cases / total pop at a certain time

Number of cases of a disease or health condition divided by the total population at a particular time

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18
Q

Prevalence Rate

A

(# of cases / population at a time) x K (constant that is 1000 or 10000)

allows for comparisons between groups or regions on a certain date!!!

something may seem worse initially but the prevalence rate can reveal that is not always the case

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19
Q

Incidence Rate

A

(# of cases / population at RISK) x K at a certain time

People who die from a disease or become immune to the disease fall out of the population at risk!!!

People who die from a disease or who recover from a disease fall out of the pool of prevalent cases because they no longer are counted as having the disease

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20
Q

Prevalence is a function of the ____ of disease and the ____ of disease

A

Incidence and Duration

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21
Q

A town has a population of 3600.
In 2003, 400 residents of the town are diagnosed with a disease.
In 2004, 200 additional residents of the town are diagnosed with the same disease. The disease is lifelong but it is not fatal.

calculate the prevalence in 2003?
calculate the prevalence In 2004?
calculate the incidence in 2004?
K=1000

A

2003 - 400/3600 x 1000 = 111 per 1000

2004 - 600 / 3600 x 1000 = 167 per 1000

Incidence of 2004: 200/3200 x 1000 = 63 per 1000

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22
Q

Analytic Epidemiology

A

Focuses on the CAUSES AND ASSOCIATIONS of states of health within a population (HOW AND WHY)

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23
Q

Things Identified or Determined in Analytic Epidemiology

A

ID causative agents, characteristics of agents, geographic patterns

Determine mode of transmission, contributing factors

involves hypothesis testing

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24
Q

3 Essential Characteristics examined in analytic epidemiology to determine how and why are …

A

Agent

Host

Environment

(The epidemiological triangle)

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25
Q

Agent

A

bacteria, virus, fungi, parasite

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26
Q

Host

A

human or animal harboring agent

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27
Q

Environment

A

physical, biological, social, and cultural factors facilitating the transmission of the agent from host to host

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28
Q

Early influence on epidemiology came from….

A

religion

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29
Q

Hippocrates and Epidemiology

A

first looked at health and disease from environmental and behavior perspectives

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30
Q

Miasma Theory

A

poisoning from foul vapors

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31
Q

Edward Jenner and Epidemiology

A

“Father of Immunology”

1798

Demonstrated small pox vaccination effectiveness

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32
Q

Germ Theory

A

microorganisms cause disease

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33
Q

John Snow and Epidemiology

A

1850

ID source of cholera epidemic to contaminated well in london

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34
Q

Florence Nightingale and Epidemiology

A

1850s

examined and tracked environmental conditions to recovery rates of soldiers in the crimean war

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35
Q

Chronic Disease Epidemiology

A

outcomes related to exposure

modifying behavior can control risk factors

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36
Q

Human Genome Project

A

New bio medical technologies can examine genetic risks

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37
Q

3 Important Triumphs in Epidemiology

A
  1. Small pox eradication thru vaccinations in 1967 to 1980 when it was declared dead by WHO
  2. cig smoking found to be major lung cancer, emphysema, and CV disease cause 1951-1963
  3. ID of auto immune deficiency syndrome (AIDS) and predicted that cause from STI. Development of prevent measures before the virus was ID’ed - 1981-1983
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38
Q

5 Important Epidemiologic Models

A
  1. Epidemiologic Triangle
  2. Wheel Model
  3. Web of Causation
  4. Chain of Infection
  5. Stages of Disease (natural history of disease)
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39
Q

Epidemiologic Triangle

A

most simple epidemi model

Factors that influence health status are:

  1. intrinsic Factors (host factors)
  2. Extrinsic factors (agent and environment)
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40
Q

The epidemiologic triangle occurs …

A

over time

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41
Q

Host Factors

A

Intrinsic factors that are the hosts ability to resist a particular infectious disease causing agent (the body forms antibodies that react with a foreign antigen and makes them harmless)

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42
Q

Examples of Host Factors

A

Genetic Susceptibility

Immutable characteristics: age, gender, race, sex

Acquired characteristics: immunological status

lifestyle factors

immunity status

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43
Q

Acquired Immunity

A

resistance to infectious agent developed from previous exposure from disease or immunization

Can be active passive or cross

44
Q

Active Immunization/Immunity

A

Administration of an antigen that can produce an antibody (vaccinations) providing more long term resistance

type of acquired immunity

45
Q

Passive Immunization/Immunity

A

transfer of specific antibody that provides short term resistance

type of acquired immunity

ex: immunoglobins (Hep A, Rabies, Tetanus); Antiserum (Ebola, Snake Anti Venom); Breastmilk

46
Q

Cross immunity

A

immunity to one agent provides a person with immunity to another agent

ex: Edward Jenner noticed that milkmaids exposed to cow pox did not get small pox

47
Q

Natural Immunity

A

innate resistance to infectious agent

48
Q

Herd Immunity

A

immunity level present in a population that has a protective effect on the population

49
Q

Extrinsic Factor Types

A

Biological

Chemical

Physical

Nutrient

Genetic

Psychological

50
Q

Biological Agent

A

bacteria

virus

fungi

parasite

51
Q

Chemical Agent

A

heavy metals

toxic chemicals

pesticides

52
Q

Physical Agents

A

radiation

heat and cold

machinery

53
Q

Nutrient Agent

A

basic dietary components needed to survive

54
Q

Genetic Agent

A

Transmitted from child to parent through genes

55
Q

Psychological Agent

A

stressful circumstances in the environment

56
Q

Important characteristics of Extrinsic Agents?

A

Infectivity

Pathogenicity

Virulence

57
Q

Infectivity

A

ability of agent to multiply, enter the host, and produce disease

58
Q

Pathogenicity

A

measures the proportion of people who develop the disease after infection

59
Q

Virulence

A

ability of agent to produce a pathological reaction resulting ins severe disease or death

60
Q

Herd Immunity is note necessarily a ___ factor, it is partly a ____ factor

A

host; environmental

61
Q

Environmental Factors

A

Extrinsic

  1. Physical (Climate)
  2. Biological Environment (living plants, animals, human pop distrib)
  3. Socioeconomic Factors (working conditions, codes, laws, herd immunity)
62
Q

Wheel model of causation

A

used to investigate:

acute and chronic diseases

infectious and non infectious processes

why some populations stay healthy while others become ill

63
Q

Compartments and their Sizes in the Wheel Model of Causation

A

Genetic Core surrounded by the Host (human)

3 sections of social environment, biological environment, and physical environment surround it

The relative size of the various compartments change depending on the specific problem under consideration

64
Q

Patterns of Disease

A

Epidemic

Endemic

Sporadic

Hyperendemic

Pandemic

65
Q

Epidemic

A

Occurrence of disease in excess of normal expectation

arises when:

  1. host, agent, and environmental factors are not in balance
  2. new agent
  3. change in existing agent (infectivity, pathogenicity, virulence)
  4. change in number of susceptible hosts in the population
  5. environmental changes that affect transmission of the agent or growth of the agent
66
Q

Endemic

A

constant and persistent presence of disease in a geographic region or population (ex: malaria in africa)

67
Q

Sporadic

A

problems with an irregular pattern; occasional cases at irregular intervals (food borne illness)

68
Q

Hyperendemic

A

persistently high number of cases (lyme disease in new jersey)

69
Q

Pandemic

A

epidemic spread of disease across geographic regions, countries, or continent’s (SARS to canada and the US)

70
Q

Web of Causation

A

model that shows direct and indirect causal relationships

displays more complex interrelationships that can increase or decrease the risk of disease!!!

*can get very complex among multiple things like cardiovascular disease for example

71
Q

Direct Causal Associations

A

no intermediate factor and is more obvious

ex: exposure to staph pathogens results in illness

72
Q

Indirect Causal Associations

A

involves one or more intervening factors and is often much more complicated

ex: a high fat diet is assoc with polyps and polyps are associated with colon cancer

73
Q

Web of Causation model States that…

A
  1. Disease never results from a single cause
  2. disease develops as a result of chains of causation
74
Q

Web of Causation model is used when …

A

A complete understanding of the causal mechanism is not prerequisite to the development of effective measures of prevention or control

75
Q

Chain of Infection

A

Infectious Agent –> Reservoir –> Portal of Exit –> mode of Transmission –> portal of entry –> susceptible host –> infectious agent repeat

76
Q

Reservoir

A

dont confuse with host

habitat in which an infectious agent usually lives, grows, and multiplies

can include animals, humans, and the environment

may or may not be the source from which an agent is transmitted

77
Q

Human Reservoirs

A

Also known as “Carriers”

carriers are persons that may be asymptomatic but capable of transmitting the agent to others

chronic carrier continuously harbors an agent (Hep B, Typhus) after an initial infection

78
Q

Zoonoses

A

animal reservoirs

animals can be host, vector, or source of certain infections and disease

Zoonosis/zoonoses is an infectious organism in VERTEBRATE animals that can be transmitted to humans through direct contact, fomite, or vector

The word comes from Zoon (animal) Noses (Ill)

ex: rabies, cat scratch fever

79
Q

Other than zoonoses, what else is an animal reservoir?

A

diseases transmitted by (vector) insects (ex; lyme disease)

80
Q

Environmental reservoirs

A

can be vehicle or airborne for example\

plant, soil, water (ex: e coli and tetanus)

81
Q

Examples of the many diseases that are zoonoses

A

Aids
Amebiasis
Anthrax
Bovine Papular Stomatitis
Brucellosis
California Encephalitis
Cat Scratch Fever
colorado tick Fever
Cowpox
Dengue Fever
Dermatophilosis
Leprosy
Lyme Disease
Pasteurellosis
Plague
Q Fever
Rabies
Rat Bite Fever
Rickettsial Pox
Rocky mounntain spotter fever
salmonellosis
shigellosis
streptococcus infections
tetanus
trichinosis
tularemia
yellow fever
zoonotic scabies

82
Q

Portal of Entry

A

the path by which agent enters susceptible host

usually the same portal they exit (ex: TB and flu)

others include: skin and the mucus membrane

83
Q

Enteric Pathogenic Atgents

A

“Fecal-Oral” portal of entry agents

84
Q

Portal of Exit

A

the path by which an agent leaves the source

usually corresponds to the site at which the agent is localized (eg TB and flu) exit the respiratory tract

some blood borne agents can exit by crossing the placenta (ex: rubella and syphilis)

85
Q

Common Portals of Entry/Exit

A

respiratory

oral

reproductive

intravenous

urinary

skin

gastrointestinal

conjunctival

transplacental

86
Q

Modes of Transmission

A

Vertical

Horizontal (Direct or Indirect [vehicle, vector, airborne])

Vector (mechanical or biological)

87
Q

Vertical transmission

A

passing of infection from parent to offspring

ex: sperm, placenta, breastmilk, contact in vaginal canal during birth

88
Q

Horizontal Transmission

A

person to person spread

can be direct or indirect

89
Q

Direct Horizontal Transmission

A

direct contact

droplet spread

(touching, kissing, biting, sexual intercourse, coughing, sneezing, large droplets in close proximity)

90
Q

Indirect horizontal Transmission

A

can be vehicle, vector, or airborne

91
Q

Vehicle Borne Indirect Horizontal Transmission

A

nonliving intermediary such as a fomite, food, water, or infectious bodily fluids that convey the infectious agent from the reservoir to a susceptible host

92
Q

Vector Borne Transmission

A

transmission via insect (mosquitoes, flies, ticks, spiders)

Does not cause disease but transmits it to the susceptible host

can be mechanical vector or biological vector

93
Q

Airborne Indirect Horizontal Transmission

A

transmitted via dust and fine particles known as aerosols

ex: TB, legionnaires, influenza

94
Q

Fomite

A

an inanimate object contaminated with the infectious agent

95
Q

Mechanical Vector

A

uninfected insect carries the agent

96
Q

Biological Vector

A

infected insect carries pathogen

97
Q

Natural history of Disease (Stages of Disease over Time)

A
  1. Stage of Susceptibility
  2. Preclinical or Presymptomatic Stage
  3. Clinical Stage
  4. Stage of Recovery, Disability, or Death
98
Q

Stage of Susceptibility

A

first stage

no disease present (pre-pathogenesis)

99
Q

Preclinical or Presymptomatic stage

A

second stage

biological onset, no signs or symptoms (pathogenesis)

there is an incubation and latency period within this

100
Q

Clinical Stage

A

third stage

signs and symptoms, medical care is sought, diagnosis is made (pathogenesis)

101
Q

Stage of Recovery, Disability or Death

A

stage 4

treatment (resolution)

102
Q

Primary Prevention can help in what part of the natural course of disease

A

susceptible hosts pre-exposure

103
Q

Secondary Prevention can help in what part of the natural course of diseases

A

Subclinical Disease Stage to clinical illness stage

104
Q

Tertiary Prevention can help in what part of the natural course of disease

A

stage of recovery, disability, or death

105
Q

Subclinical Disease Stage marks…

A

the beginning of pathological process and changes within the body

it is then followed by onset of symptoms then diagnosis sought which is then followed by the clinical illness stage